OPTICAL SWITCH

Abstract: An optical switch which comprises an optical fiber arrangement member to which free end portions of a plurality of first optical fibers are fixed, a movable arm opposed to the optical fiber arrangement member and securing free end portion of a second optical fiber, and a driving means for switching the optical connection by driving the optical fiber arrangement member and/or the movable arm in the direction of arrangement of the first optical fibers and in the direction perpendicular to the mentioned direction so as to optically connect the second optical fiber to the first optical fibers. The optical fiber arrangement member and movable arm are housed in a sealed case, in which an optical reflection preventing agent is sealed.

Description: Technical Field The present invention relates to an optical switch, and particularly to an optical switch for optical coupling between a plurality of first optical fibers juxtaposed on an optical fiber arranging member and a second optical fiber movable along the optical fiber arranging member. Background Art EP-A1-0 569 981 discloses an optical switch comprising means for arranging members, each of the members having first optical fibers, a convey mechanism for conveying at least one second optical fiber to each of the first optical fibers of the arranging means to connect the second optical fiber with the first optical fiber, and means for introducing the second optical fiber to the first optical fiber with fiber introduction grooves for guiding an end portion of the second optical fiber to the first optical fiber. The arranging means may have an optical fiber arranging member for arranging a plurality of optical fibers, comprising a fiber arranging member having first optical fibers that are arranged linearly or planarly, and the fiber introduction grooves for guiding an end portion of the second optical fiber may be formed ahead of end portions of the first optical fibers. The above fiber arranging member may also be constituted by a substrate having a plurality of fiber fixing grooves formed in an upper surface thereof, and the first optical fibers fixed in the fiber fixing grooves. The fiber fixing grooves and the fiber introduction grooves may constitute integrally formed substantially V-grooves. A guide serving as a reference to position and fix the fiber introduction grooves may be formed in the fiber arranging member. The above fiber arranging member may be constituted by a member in which a plurality of fiber fixing holes are formed, and the first optical fibers fixed in the fiber fixing holes. A guide means serving as a reference to position and fix the fiber fixing holes and the fiber introduction grooves may be formed. According to EP-A1-0 569 981 there is provided an optical fiber arranging member in which fiber fixing means having grooves or holes and fiber introduction grooves are formed in the same member and a plurality of optical fibers are fixed to the fiber fixing means, and in which a slit is present between the fiber fixing means and the fiber introduction grooves. There are known optical scan switches provided with a connector table in which a lot of connectors are arranged in a matrix and are to be connected to a master connector which is two-dimensionally movable ("C-449, 10-path-batch 1 × 1000 optical scan switch," Spring Meeting (1998), Institute of Electronics, Information and Communication Engineers of Japan, P4-238). The conventional connector table, however, achieved the two-dimensional arrangement of optical fibers by physically arranging a plurality of connectors in a matrix. Thus, the arrangement was not accurate between optical fibers held by different connectors, thereby exhibiting a defect that they were not able to be connected with accuracy with an optical fiber held in the master connector. Disclosure of the Invention The optical switch of the present invention has been accomplished to solve the above problem, and specifically, an object of the invention is to stabilize optical characteristics in optically coupling a movable-side optical fiber with a stationary-side optical fiber, to improve reliability of optical coupling, and to improve positioning accuracy upon optical coupling. An optical switch according to the present invention has the features which are recited in independent claim 1 or 2. Preferred embodiments of the invention are indicated in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 32 is an overall perspective view to show a first embodiment of the optical switch of the present invention. Fig. 33 is a cross section of Fig. 32. Fig. 34 is a plan view of part A in Fig. 32. Fig. 35 is a side cross section of Fig. 34. Fig. 36 is a bottom plan view of an enlarged movable head. Fig. 37A is a cross section along B-B line in Fig. 36, and Fig. 37B is a drawing to show an engagement relation between guide pins and second fiber fixing grooves as a modification of Fig. 37A. Fig. 38 is a perspective view of an optical fiber arranging member enlarged. Fig. 39 is a longitudinal cross section of Fig. 38. Fig. 40 is a perspective view of a movable arm with a movable head attached thereto. Fig. 41 is an exploded perspective view to show a second movable arm, a movable head, and a mount stage. Fig. 42 is a perspective view of assembly of Fig. 41. Fig. 43 is a side view to show a state in which a first movable arm is attached to the mount stage. Fig. 44 is a side view to show a state in which the second movable arm with a movable head is attached to the mount stage. Fig. 45 is a side view to show an assembled state of the first movable arm of Fig. 43 and the second movable arm of Fig. 44. Fig. 46 is an exploded perspective view of the movable arm. Fig. 47 is a perspective view to show an assembled state of the movable arm of Fig. 46. Fig. 48 is a developed plan view of a plate spring composing the second movable arm. Fig. 49 is an enlarged drawing of inside of circle C in Fig. 48. Figs. 50A and 50B are side view and plan view to show the second movable arm. Fig. 51 is a perspective view to show an engagement relation between the second optical fibers and guide pins supported by the movable head, and the fiber introducing grooves. Figs. 52A and 52B are side view and plan view of the second movable arm. Figs. 53A and 53B are plan view and front elevation to show a state of initial engagement between the second optical fibers and guide pins supported by the movable head, and the fiber introducing grooves. Figs. 54A and 54B are plan view and front elevation to show a state of engagement between the second optical fibers and guide pins supported by the movable head, and the fiber introducing grooves. Fig. 55 is a schematic drawing to show an end face separation in a state in which optical axes of first and second optical fibers are aligned. Fig. 56 is a schematic drawing to show an end face separation in a state in which optical axes of first and second optical fibers are inclined to each other. Fig. 57 is a plan view to show a deformed state due to thermal expansion, of the movable arm. Best Mode for Carrying out the Invention Preferred embodiments of the optical switch according to the present invention will be described in detail by reference to the drawings. A first embodiment of the optical switch of the present invention is next described by reference to the drawings. As shown in Fig. 32, an optical switch 211 is provided with an optical fiber arranging member 203 and a drive mechanism 224 for second optical fibers 204 on the master side, on the top surface of base 212. The optical fiber arranging member 203 is mounted on a first support stage 216. The first support stage 216 is mounted with securing screws 214 to a second support stage 215, and the second support stage 215 is fixed with securing screws 214 on the base 212. The optical fiber arranging member (optical fiber unit) 203 has a base plate 206 having first fiber fixing grooves 208 and second fiber fixing grooves (fiber introducing grooves) 209 on the top surface thereof, and first optical fibers 202 in a multipath optical fiber tape 201 are fixed in the first fiber fixing grooves 208. The second optical fibers 204 are supported on a movable head 205 driven by a drive mechanism 224 (as detailed later) and are arranged to move in the arrangement directions of the first optical fibers 202 (or the X directions) and in the directions (or the Y directions) perpendicular to the fiber arrangement directions (or the X directions). As shown in Fig. 38 and Fig. 39, the optical fiber arranging member 203 is composed of a base plate 206, a separate groove 207 formed on the top surface of the base 206, first fiber fixing grooves 208 and second fiber fixing grooves 209 arranged on the both sides of the separate groove 207 as extending in the direction perpendicular to the longitudinal direction of the separate groove 207, and a cover plate 210 for pressing the first optical fibers 202 from the top. The base plate 206 is approximately rectangular as shown in Fig. 38, and the separate groove 207 extends from one side surface 206a to the other side surface 206b of the base plate 206. A cross section of the separate groove 207 is approximately U-shaped. On the other hand, a multiplicity of (for example, 80, some of which are illustrated) first fiber fixing grooves 208 and second fiber fixing grooves 209 are arranged at constant pitch intervals (for example, 0.25 mm) from one side surface (reference end face) 206a of the base plate 206. Further, the first and second optical fiber fixing grooves 208, 209 are V grooves in this embodiment, and are arranged so that longitudinal extension lines thereof along the respective fiber fixing grooves 208 and 209 coincide with each other. The first optical fibers 202 exposed from the optical fiber tape 201 are inserted into the first fiber fixing grooves 208 from the rear of the fiber fixing grooves 208, and are arranged so that fiber tip faces 202a are aligned on a same plane with one vertical wall of the separate groove 207. The separate groove 207 is approximately U-shaped as described above and the depth thereof is a little deeper than the fiber fixing grooves. The above first optical fibers 202 are inscribed in side walls of the bottom parts of the V grooves, and are held in this state with an adhesive. Also, the silicon cover plate 210 is bonded to the top surface of the base plate 206 to protect the first optical fibers 202 fixed in the first fiber fixing grooves 208. Since the cover plate 210 is bonded to the base plate 206 as exposing the tip faces of the first optical fibers 202, there is no trouble with connection to the second optical fibers 204. Further, since the V grooves are deep enough to fully embed the first optical fibers 202, the cover plate 210 is bonded in an almost surface contact state to the top surface of the base plate 206. As shown in Fig. 38, steps 213 are formed at the tip ends of the second fiber fixing grooves 209 by cutting the crests of the V grooves; the steps 213 are next to the separate groove 207, and have a width L throughout the entire length, and a predetermined height h from the bottom of the base plate 206. Therefore, when the second optical fibers 204 are inserted into the second fiber fixing grooves 209 to make optical coupling between the second optical fibers 204 and the first optical fibers 202, the second optical fibers 204 project from the steps 213 as shown in Fig. 33. Then the second optical fibers 204 projecting from the steps 213 are urged against the steps 213 by a fiber stop 257 (Fig. 35), so that the second optical fibers 204 are surely secured in the second fiber fixing grooves 209. In the present embodiment, the second optical fibers 204 include a plurality of (for example, two, six, or eight) optical fibers attached in a set to the movable head 205 and moving together, so that a plurality of optical paths can be switched at a time. The base plate 206 of the above optical fiber arranging member 203 is made of a Si material, and in molding thereof, the top surface of a base plate 206 is cut by a diamond cutter or the like from one side surface 206a to the other side surface 206b to form the separate groove 207 and steps 213. Also, the top surface is cut in a plurality of V grooves by the diamond cutter or the like along the direction perpendicular to the longitudinal direction of the separate groove 207 and steps 213 to form the first and second fiber fixing grooves 208, 209. Then the elongate base plate 206 is cut in an appropriate length, thereby easily producing the base plate 206 in the predetermined length as shown. Also, it can be produced with high accuracy by the photoetching technology (though not shown). In the illustrated example the first and second fiber fixing grooves 208, 209 are formed in a single base plate 206, but another possible arrangement may be constructed in such a structure that the first and second fiber fixing grooves 208, 209 are formed on top surfaces of two base plates juxtaposed next to each other and the fiber fixing grooves 208, 209 are arranged to be aligned on same lines. Here, the movable head 205 shown in Fig. 32 moves in the directions (the Y directions) perpendicular to the arrangement directions of the second fiber fixing grooves 209 within a predetermined range, and also moves in the arrangement directions (the X directions) of the second fiber fixing grooves 209, whereby the second optical fibers 204 can leave the second fiber fixing grooves 209 and can move over the crests of the fiber fixing grooves into other second fiber fixing grooves 209. As a consequence, the optical coupling between the first optical fibers 202 and the second optical fibers 204 can be suitably switched. Further, the second optical fibers 204 extending above the steps 213 of the second fiber fixing grooves 209 are pressed by the fiber stop 257 (Fig. 35) to be surely fixed in the second fiber fixing grooves 209. This keeps the second fibers 204 from floating from the second fiber fixing grooves 209 with application of external stress, whereby the second fibers 204 can be surely optically coupled with the first optical fibers 202. Incidentally, the second optical fibers 204 are supported on the movable head 205, as described above; the movable head 205 can be accurately positioned to the optical fiber arranging member 203 by the special ideas for the structure of the movable head 205 and the supporting means of the second optical fibers 204 to the movable head 205, and the structure of the optical fiber arranging member 203 corresponding thereto. Further, the movable head 205 is stationary in the arrangement directions of optical fibers with application of external stress, thus achieving the structure that can stably hold the second optical fibers 204 in the second fiber fixing grooves 209. In the present embodiment it is preferred to arrange the movable head 205 and optical fiber arranging member 203 in the following structure. As shown in Fig. 34 to Fig.37, a fiber fixing block 217 is mounted in a front-down state to a slant surface 253 formed by cutting the bottom rear part of the movable head 205 (Fig. 35). The second optical fibers 204 are fit in fitting grooves 217a in the bottom surface of the fiber fixing block 217, a stop plate 217b is put on the outer peripheries of fibers, and the stop plate 217b is bonded to the fiber fixing block 217 with an adhesive. As a result, the second optical fibers 204 are arranged at constant intervals to the movable head 205 and the tip ends of the second optical fibers 204 can be mounted as inclined in a front-down state. As shown in Fig. 37A, a pair of pin fixing grooves 218 of V grooves parallel to the second optical fibers 204 are formed by cutting outside the two second optical fibers 204 in the tip end of the bottom surface of the movable head 205. A pair of guide pins (positioning members) 219 made of a hard metal material are fit and secured in the pin fixing grooves 218, and a portion of the outer periphery of each guide pin 219 projects from the bottom surface of the movable head 205. In Fig. 37A the pin fixing grooves 218 are formed in the fixing block 205a and the fixing block 205a is fixed in a recess 205b of the movable head 205, and this arrangement is for convenience of fabrication. Also, when the second optical fibers 204 are inserted into the second fiber fixing grooves 209, the second optical fibers 204 are bent, and thus, a recess 205c is formed as an escape space thereof in the fixing block 205a. On the other hand, guide grooves (engaging portions) 220 of V grooves for the above guide pins 219 to fit are formed in parallel with the second fiber fixing grooves 209 in the optical fiber arranging member 203. Accordingly, when the movable head 205 is lowered from above the optical fiber arranging member 203, the tip ends of the second optical fibers 204 come to fit in the second fiber fixing grooves 209 as being bent with the fixed portions to the fiber fixing block 217 as a fulcrum, so as to be optically coupled with the first optical fibers 202. Further lowering the movable head 205, the guide pins 219 projecting from the bottom surface of the movable head 205 come to fit in the guide grooves 220. Supposing in this state a push-down force is continuously applied to the movable head 205 through the movable arm 228, the movable head 205 is kept stationary in the X directions even with application of external stress on the movable head 205 in the arrangement directions (the X directions) of the first optical fibers 202 because the guide pins 219 made of the hard metal are in mesh with the guide grooves 220, whereby optical coupling can be surely held between the first and second optical fibers 202, 204. Cross sections of the guide pins 219 and guide grooves (engaging portions) 220 may be not only of recessed shapes, but also of projected shapes. In case of the engaging portions 220 being projected, positioning recesses (not shown) are preferably formed in the movable head 205 instead of the guide pins. Further, there is no restriction on the number of guide pins 219. The example shown in Fig. 37A includes two parallel guide pins arranged at a predetermined interval, but the intended purpose can be achieved simply by even one guide pin 219. In case of a single guide pin 219, appropriate support means is preferably added for preventing the movable head 205 from being inclined. Fig. 37B shows an embodiment in which the second fiber fixing grooves 209 are also used for the guide grooves to fit with the guide pins 219. In case of Fig. 37B, the width of openings of V grooves of the second fiber fixing grooves 209 is set to about 250 mµ. Further, the outer diameter of optical fibers is about 125 µm, and the outer diameter of the guide pins 219 is set to 230 to 250 µm. According to the structure of Fig. 37B, because the second fiber fixing grooves 209 also serve as the guide grooves, the second optical fibers 204 can fit in the second fiber fixing grooves 209 in a sufficient depth, and the guide pins 219 can also fit in the second fiber fixing grooves 209 in part thereof. Continuously applying a slight pressing force from above the movable head 205 while parts of guide pins 219 are fit in the second fiber fixing grooves 209, the movable head 205 is kept stationary in the X directions even with application of external stress on the movable head 205 in the fiber arrangement directions (the X directions) to be accurately positioned, thus achieving the intended purpose. The movable head 205 is located at the tip of the movable arm 228, the movable arm 228 is composed of first movable arm 226 and second movable arm 227 having elasticity, and the first movable arm 226 and second movable arm 227 are arranged up and down with a gap. The base end of the movable arm 228 is fixed to a mount stage 236 provided in a second movable member 235B of the second drive mechanism 224A and is interlocked with a first motor 229 as a drive source. The drive mechanism 224 for moving the movable arm 228 will be described in detail. First described is a first drive mechanism 224A for driving the movable arm 228 in the arrangement directions of the first optical fibers 202. As shown in Fig. 32 and Fig. 33, the first drive mechanism 224A is provided with the first motor 229 as a drive source, the first motor 229 is disposed on one side end of the base 212, and a screw shaft 230 connected to a motor shaft of the first motor 229 is horizontally set on the base 212 through a bearing plate 231. This screw shaft 230 is interlocked with a first movable member 235A composing a part of the movable member 232. Namely, there are provided a stop arm 233 and an engaging wire 234 with spring property at the rear end (the left end in Fig. 32) of the first movable member 235A, the stop arm 233 holds the screw shaft 230, and the engaging wire 234 is engaged with a screw groove in the screw shaft 230. Accordingly, with forward and backward rotation of the screw shaft 230, the first movable member 235A moves left and right along the screw shaft 230. The first movable member 235A is fixed on the top surface of the second movable member 235B of a plane plate composing a part of the movable member 232. A block mount stage 236 is fixed on the top surface of the second movable member 235B, and each of the base ends of the first movable arm 226 and second movable arm 227 of the movable arm 228 is fixed with plural securing screws 237 to the mount stage 236. As shown in Fig. 33, a guide block 238 is provided on the bottom surface of the second-movable member 235B of a plane plate. This guide block 238 is slidably fit in an opening portion of a U-shaped guide member 240 fixed in a guide groove 239 on the top surface of the base 212. Accordingly, as shown in Fig. 32, the guide block 238 moves along the guide member 240, whereby the second movable member 235B stably moves as keeping a predetermined posture. First shield plate 242 and second shield plate 243 are fixed to the both ends of the top surface of the second movable member 235B. Also, a pair of left and right, optical, first and second limit sensors 244A, 244B are provided on the base 212. Here, when the first shield plate 242 interrupts light from the first limit sensor 244A, movement toward one side of the second movable member 235B is stopped. Also, when the second shield plate 243 interrupts light from the second limit sensor 244B, movement toward the other side of the second movable member 235B is stopped and the position of the origin of the second movable member 235B is detected. Each stopper denoted by numeral 245A, 245B is a member for mechanically and forcibly stopping left-and-right (X-directional) movement of the second movable member 235B by coming into contact with the side surface of the second movable member 235B when the first and second unit sensors 244A, 244B are out of order. A first embodiment of the first and second movable arms 226, 227 composing the movable arm 228 is shown in Fig. 40 to Fig. 45. Referring to these drawings, the first movable arm 226 is formed from a metal plate with spring property, and the base end thereof is fixed with securing screws 237 on the top surface of the mount stage 236. The first movable arm 226 is formed to decrease the width toward the tip in order to increase the flexibility, and a bent portion provided at the tip of the first movable arm 226 is arranged to press the top surface of the movable head 205. Also, a nearly C-shaped receiver 251 is fixed at the middle position of the bottom surface of the first movable arm 226. A second movable arm 227 is constructed in a laminate structure of a plurality of thin plate springs, and the laminate plate springs 227a are arranged in a zigzag fashion by alternately spot-welding the both end portions of the laminate plate springs 227a. Further, the base end portion of the uppermost plate spring 227b is hook-shaped, and holes 221 perforating bent portions 227c are positioned with respect to screw holes 223 in a front projecting portion 236a of the mount stage 236, and securing screws 237 are screwed into the screw holes 223 through a washer 222, thereby securing the uppermost plate spring 227b to the mount stage 236. Further, a pair of left and right bent portions 227e are formed on either side of the lowermost plate spring 227d, a rear portion of the movable head 205 is fit to an internal wall surface of each bent portion 227e, and thereafter the movable head 225 is fixed to the bent portions 227e with an adhesive. Since the second movable arm 227 has the structure of the plate springs 227a connected in a zigzag fashion as described above, the zigzag intermediate layers formed between the uppermost plate spring 227b and the lowermost plate spring 227d become expandable or contractible, whereby the movable head 205 can be softly and elastically supported. Particularly, because the present embodiment employs the spring structure of plural plate springs arranged in lamination and in a zigzag connection, the spring length can be kept substantially long in a smaller space and a soft spring with more flexibility can be constructed, thereby enabling smooth elastic support of the movable head 205. Accordingly, as shown in Fig. 32, the movable head 205 is supported by the tip of the second movable arm 227, and thus is driven by the second drive mechanism 224B perpendicular to the arrangement directions (X directions) of the first optical fibers 202 (in the Y directions). The second drive mechanism 224B is provided with a second motor 246 as a drive source for moving the movable- arm 228 in the Y directions, and the second motor 246 is disposed on one side end of the base 211. A sector gear 248 is in mesh with a motor pinion 247 of the second motor 246. This sector gear 248 is fixed on a shaft 252 projecting from an end portion of an actuator rod 249, and the actuator rod 249 is formed from a shaft with an offset axis or a shaft of a non-circular cross section. The both end shafts 252 of the actuator rod 249 are supported by a bearing plate 250 fixed on the base 212. A C-shape receiver 251 is fixed on the bottom surface of the first movable arm 226, and the bottom surface of the receiver 251 is arranged as slidable in press contact with the peripheral surface of the actuator rod 249. Thus, driving the second motor 246, the actuator rod 249 rotates by a predetermined angle about the shafts 252 through the motor pinion 247 and sector gear 248. As a result, the actuator rod 249 performs the cam operation about the shafts 252 to move the receiver 251 in press contact with the peripheral surface of the actuator rod 249 up and down. Therefore, the first movable arm 226 and second movable arm 227 move together up and down, which moves the movable head 205 for the second optical fibers 204 up and down. Namely, when the actuator rod 249 rotates to lower the point of action thereof, the movable arm 228 also descends by its own elasticity, whereby the second optical fibers 209 are pressed against groove bottoms of the second fiber fixing grooves 204. This pressing state is also held when the second motor 245 is in a non-operating state. On the other hand, when the actuator rod 249 further rotates to raise the point of action thereof, the movable arm 228 is lifted up through the receiver 251 against the elasticity, whereby the second optical fibers 204 supported by the movable head 205 leave the second fiber fixing grooves 209. When the movable head 205 is lowered, the guide pins 219 come to engage with the guide grooves 220, which certainly prevents deviation of the movable head 205 in the fiber arrangement directions. As described above, with the driving mechanism 224 in the present embodiment, driving the first motor 229 composing a part of the structure of the first drive mechanism 224A and the second motor 246 composing a part of the structure of the second drive mechanism 224B, the movable head 205 supporting the second optical fibers 204 can move in the arrangement directions of the first optical fibers 202 (in the X directions) and in the directions (the Y directions) perpendicular to the arrangement directions (the X directions) of the first optical fibers 202, whereby the second optical fibers 204 can be removed from a set of grooves out of the second fiber fixing grooves 209 and smoothly move toward other second fiber fixing grooves 209, thereby switching optical connection between the first optical fibers 202 and the second optical fibers 204. The present embodiment is arranged to transmit the motion of the actuator shaft 249 rotated by the second motor 246 through the receiver 251 to the first movable arm 226 and then to transmit it through the first movable arm 226 to the second movable arm 227. The invention, however, may employ such an arrangement that the rotation of motion of the actuator rod 249 is directly transmitted to the second movable arm 227, and in case of such an arrangement, the first movable arm 226 can be omitted (though not shown). A second embodiment of the movable arm is next described referring to Fig. 51 to Fig. 57. In the second embodiment, the structure of second movable arm 298 is different from that of the second movable arm 227 in the first embodiment. It is first described with reference to Fig. 51 to Fig. 57. Fig. 51 is a partial, enlarged, perspective view of the movable head 205 in the optical switch of the V groove guide method. Guide pins 219 for positioning are attached to the movable head 205, and by pressing the movable head 205 in the Y directions, the guide pins 219 are fixed in the fiber introducing grooves 291 of a V-groove shape in the optical fiber arranging member 281, whereby the second optical fibers 204 are positioned as aligned in optical axis with the first optical fibers (not shown). As shown in Fig. 52, a plate spring 295 composing the movable arm connects the movable head 205 with a mount stage 236 provided in the second movable member 235B of the first drive mechanism 224A. Provided in a spring base end 261 of this plate spring 295 are fixing portions 267 for fixing the plate spring 295 to the mount stage 236 provided in the second movable member 235B of the first drive mechanism 224A, and screw insertion holes 262 are formed in the fixing portions 267. A vertical portion 263 rising from the ends of the fixing portions 267 is formed in the spring base end 261, and a spring body portion 264 extends horizontally from the upper end of the vertical portion 263. This spring body portion 264 is constructed in a lamination structure of a plurality of plate springs, and has a zigzag portion 265 formed by welding one end portions of plate springs in upper and lower layers in a zigzag fashion, and a portion extending forward from the lower end of the zigzag portion 265 composes a movable head mount portion 266. The above plate spring 295 has flexibility in the X directions and in the Y directions as shown by dashed lines in Figs. 52A and 52B, so that the movable head 205 has flexibility in the directions. Accordingly, even if the movable head 205 is positioned as deviated from centers of predetermined fiber introducing grooves 291 (Fig. 53), the moving head 205 is urged in the Y direction in Fig. 52A so as to smoothly position the guide pins 219 in the centers of grooves along the slopes of the fiber introducing grooves 291 (Fig. 54). Incidentally, since the plate spring 295 having the above zigzag portion 265 is constructed in the laminate structure of a plurality of spring plate members of plane plates, there is a possibility of positional deviation of the movable head 205 when it is placed under high-temperature environments because deformation due to thermal expansion of the plate spring 295 itself or deformation due to thermal expansion of peripheral structures surrounding the plate spring 295 is transmitted to the movable head mount portion 266. When this positional deviation occurs because of thermal expansion of peripheral structures around the plate spring 295, the optical axes are likely to be inclined to each other in the end face portions of the first and second fibers 202, 204 as shown in Fig. 55 and Fig. 56, which would cause variations of the end face separation x to x + α, thus raising a problem that the optical characteristics become unstable. When the plate spring 295 itself is thermally expanded, the plate spring 295 is deformed as shown by the dashed line in Fig. 57. In this case, the movable head 205, provided on the movable head mount portion 266 at the tip of plate spring 295, also has positional deviation; then, even if the movable head 205 is positioned to the predetermined fiber introducing grooves 291, the end face separation would change between the first and second optical fibers 202, 204, resulting in adversely affecting the optical characteristics. In the next place, a third embodiment of the movable arm solving the above problems is explained by reference to Fig. 46 to Fig. 50. Same or like constituent portions as those in the second embodiment of the movable arm as described above will be denoted by the same reference numerals. In this embodiment, the movable arm 297 is constructed in an assembly of the first movable arm 226 and the second movable arm 296, and a fixing portion 267 of the first movable arm 226 and the second movable arm 296 is fixed to the mount stage 236 provided in the second movable member 235B of the first drive mechanism 224A. When the mount stage 236 is moved back and forth in the directions of the arrow in Fig. 46, the movable head 205, attached to the tip of the second movable arm 296, moves in the fiber arrangement directions, thereby switching the optical paths. Describing in further detail, one end of the second movable arm 296 has a spring base end 261 of plate, a wing fixing portion 267 is formed in the spring base end 261, and screw insertion holes 262 are formed through the fixing portion 267. Then securing screws 269 are inserted into the screw insertion holes 262 to be meshed with screw holes 271 formed in a lower projecting portion 270 of the mount stage 236, thereby fixing the second movable arm 296 to the mount base 236. A vertical portion 263 rising from the tip of the fixing portion 267 is integrally formed in the spring base end 261 of the second movable arm 296, a spring body portion 264 extending forward is integrally formed from the upper end of the vertical portion 263, and a movable head mount portion 266 for fixing the movable head 205 is formed at the fore end of the spring body portion 264. The second movable arm 296 is formed by blanking of a spring plate of a plane plate, as shown in Fig. 48. The spring body portion 264 as-described above is provided with first flexible portions 287 extending from the movable head mount portion 266 toward the spring base end 261 and integrally formed through first connecting portions 289 with one end of the movable head mount portion 266, a second flexible portion 285 extending from the spring base end 261 to the movable head mount portion 266 and integrally formed through a second connecting portion 294 with one end of the spring base end 261, and third flexible portions 286 connecting the tips of the first flexible portions 287 with the tip of the second flexible portion 285 through third connecting portions 283 and fourth connecting portions 284. The first flexible portions 287 as described above are comprised of two strips parallel to each other, which are located outermost of the plate body portion 264 on the both sides of the plate body portion 264. The second flexible portion 285 is comprised of one straight strip, which is located at the center of the spring body portion 264. The third flexible portions 286 are comprised of two strips parallel to each other, and are located between the first flexible portions 287 and the second flexible portion 285. Here, the first flexible portions 287 and the third flexible portions 286 are separated from each other through first slit portions 275 extending in the longitudinal direction of the spring body portion 264, while the second flexible portion 285 and the third flexible portions 286 are separated from each other through second slit portions 276 extending in the longitudinal direction of the spring body portion 264. Also, a third slit portion 274 is formed as bridging between the ends of two first slit portions 275 on the side of the movable head mount portion 266, and at the ends of two second slit portions 276 fourth slit portions 277 are formed as extending toward the both sides of the spring body portion 264 and reaching the outside of the second movable arm 296. Further, this third slit portion 274 is located closer to the movable head mount portion 266 than the fourth connecting portions 284 and the fourth slit portions 277 are located closer to the spring base end 261 than the third connecting portions 283. Accordingly, between the spring base end 261 and the movable head mount portion 266, the spring body portion 264 is formed in an S-shape structure continuously connected by the one first flexible portion 287, one third flexible portion 286, and center second flexible portion 285 and in another S-shape structure continuously connected by the other first flexible portion 287, other third flexible portion 286, and center second flexible portion 285. Also, bent portions 279 are provided on the both sides of the second movable arm 296, and because the bent portions 279 are provided on extensions of the first slit portions 275, the first slit portions 275 are located at corners when the second movable arm 296 is formed by bending as shown in Fig. 50. Further, V-shape cut-outs 288 are formed between the spring body portion 264 and the movable head mount portion 266, and the cut-outs 288 are formed near the first connecting portions 289. Now, in Fig. 49, supposing a pressing force in the Y direction is applied to the movable head mount portion 266, the first, second, and third flexible portions 287, 285, 286 of the spring body portion 264 are elastically deformed into a zigzag shape. As a result, the second movable arm 296 can become a spring mechanism with flexibility. As shown in Fig. 46 and Fig. 47, the tip of the first movable arm 226 having a C-shape receiver 251 is positioned on the top surface of the movable head mount portion 266 of the second movable arm 296. Screw insertion holes 290 are formed in the base end of the first movable arm 226, and securing screws 237 are inserted into the screw insertion holes 290 and the securing screws 237 are screwed into screw holes 292 formed in a raised top surface 293 of the mount stage 236 to secure the base end of the first movable arm 226 to the mount stage 236. In the present embodiment, similarly as in the first embodiment of the movable arm, the tip end of the first movable arm 226 moves up and down through the receiver 251 in contact therewith with rotation of the actuator rod 249 (Fig. 32), thereby moving the movable head mount portion 266 of the second movable arm 296 up and down. On this occasion, the second movable arm 296 is bent in accordance with the movable head mount portion 266, but because the second movable arm 296 is formed from a spring plate and has the first to fourth slit portions 275 to 277 formed therein, X-directional and Y-directional stiffness is lower than a plate spring formed without slit portions and in the same dimensions, which increases flexibility to that extent. As described above, the second movable arm 296 requires just a small force for deformation in the X directions and the Y directions in Fig. 32 because it has lower stiffness. Thus, a compact second motor 246 can be used to press the movable head 205 of Fig. 32 against the second fiber fixing grooves 209, thereby miniaturizing the optical switch to that extent. Further, because the second movable arm 296 has low stiffness in the X directions, the guide pins 219 are smoothly.positioned along the V grooves even if the second movable arm 296 is positioned to the second fiber fixing grooves 209 in a somewhat offset state of positioning of the movable head 205, thereby improving positioning accuracy of the second optical fibers 204. Further, because the first to fourth slit portions 274 to 277 are formed in the second movable arm 296, the slit portions work to absorb deformation due to thermal expansion. Fig. 49 shows an enlarged view of the circle in Fig. 48, and shows a state of deformation due to thermal expansion, of the second movable arm 296 in the outstanding portion. As shown in Fig. 49, with thermal expansion of the second movable arm 296, thermally expanded portions are arranged to effectively avoid deformation thereof, as indicated by the dotted lines, through a clearance between the third and fourth slit portions 274, 277, so that the deformation can be prevented from reaching the movable head mount portion 266. Therefore, the movable head 205 is stationary in the longitudinal direction of optical fibers and variations become decreased in end face separation between the first and second optical fibers 202, 204. Fig. 50 is a drawing to show a modification of the second movable arm 296. In this modification, the movable head mount portion 266 of the second movable arm 296 is preliminarily inclined upward by a predetermined angle α relative to the spring body portion 264. This is for taking account of that the movable head 205 descends as getting parallel to the fiber introducing grooves 291 when the movable head 205 having the guide pins 219 on the bottom surface is pushed down as indicated by the chain double-dashed lines in Fig. 50. Namely, the movable head mount portion 266 is arranged as inclined upward by the predetermined angle α in a non-pressed state of the movable head 205, so that the guide pins 219 are also inclined upward. After the movable head mount portion 266 is pressed down from the state indicated by the solid lines in Fig. 50, it comes to the position of the chain double-dashed lines in the same drawing, whereby the movable head 205 becomes parallel to the second fiber fixing grooves 209. Thus, the movable head 205 and guide pins 219 can always contact the second fiber fixing grooves 209, whereby the movable head 205 can be positioned with accuracy to the second fiber fixing grooves 209. The movable arm 297 in the embodiment shown in Fig. 50 may employ such a structure that the motion of the actuator shaft 249 rotated by the second motor 246 shown in Fig. 32 is directly transmitted to the second movable arm 296, and in case of this structure, the first movable arm 226 can be omitted (though not shown). Also, this embodiment employs the first movable arm 226 in the same structure as the first embodiment of the movable arm, wherein the tip of the first movable arm 226 is positioned on the top surface of the movable head mount portion 266 in the second movable arm 296. In this case, there occurs a doubt that deformation due to thermal expansion in the longitudinal direction of the first movable arm 226 could affect the second movable arm 296. With regard to this point, because the first movable arm 226 has a right-angle step 226a that can absorb thermal expansion in the longitudinal direction thereof and the movable head 206 is attached not to the first movable arm 226, but to the second movable arm 296, little deformation due to thermal expansion of the first movable arm 226 affects the movable head mount portion 266 at the tip of the second movable arm 296, thereby avoiding degradation of the operation and effects based on the above structure of the second movable arm 296. The above embodiments each showed the examples of the drive mechanism 224 for optical switch in which the optical fiber arranging member 203 is constructed in a single step. The present invention, however, is by no means limited to the examples, but it can be applied to optical switch apparatus constructed in such an arrangement that the optical fiber arranging member 203 is formed in multiple steps and a drive mechanism (not shown) using a two-dimensional or three-dimensional moving stage is used to switch optical connection between the second optical fibers and the first optical fibers in the respective steps. Next described are the effects in the embodiment of the optical switch as described above. When the master-side second optical fibers 204 are guided into the fiber introducing grooves 209 to be optically coupled with the multipath-side first optical fibers 202, the positioning members 219 provided in the movable head 205 supporting the second optical fibers 204 come to fit with the fiber introducing grooves 209 or the engaging portions 220 provided along the fiber introducing grooves 209, which presents the effect that with application of external stress in the fiber arrangement directions on the second optical fibers 204, no deviation of optical axis occurs in the optical coupling portion, whereby optical coupling between optical fibers facing in end facets can be securely maintained. Also, because the movable head 205, in which the positioning members 219 are provided, has flexibility, the second optical fibers 204 can be smoothly introduced into the fiber introducing grooves 209; and because the movable head 205 is urged downward by the elasticity of the movable arm 228 to be surely pressed against the fiber introducing grooves 209, stable optical coupling of optical fibers can be realized even when a force acts in the direction to separate the second optical fibers 204 from the fiber introducing grooves 209. Since the second movable arm 227 is constructed in the structure of the plate spring that can expand or contract in the zigzag form, the stiffness of the second movable arm 222 can be decreased to increase flexibility and the movable head 205 can be smoothly pressed toward the fiber introducing grooves 209 with a small force, thereby enabling miniaturization of actuator and in turn miniaturization of optical switch. The above effects are further enhanced when the second movable arm 298 is formed by bending a single plate spring with slit portions. Further, in case of the second movable arm 298 having the slit portions, even if it is deformed due to thermal expansion, the deformation is smoothly absorbed by the slit portions. Thus, there occurs no variations in end face separation between the first and second fibers 202 and 204, whereby the variations in optical characteristics can be minimized. Here, the optical switches according to the present invention can achieve the following effects because of the above structures thereof. Namely, because the antireflection agent is interposed in the optical coupling portion between the master-side second optical fibers and the multipath-side first optical fibers, diffusion of light can be suppressed even if the fiber end facets of the optical fibers opposed to each other are not in contact with each other, thus presenting the effect of decreasing the optical coupling losses; in addition, because the antireflection agent is confined in the sealing case, it is prevented from escaping in vapor and dust or the like is prevented from intruding into the sealing case. Therefore, the invention can realize stabilization of optical characteristics in optically coupling the first optical fibers with the second optical fibers, improvement in reliability of optical coupling, and improvement in positioning accuracy upon optical coupling. The present invention was described in detail specifically with the preferred embodiments, but it should be noted that the invention involves modifications and changes thereof in the range not departing from the true spirit and scope of the invention.

Claims: An optical switch comprising: an optical fiber arranging member (203) having a plurality of fiber fixing grooves (208) for fixing a plurality of first optical fibers (202) and a plurality of fiber introducing grooves (209) for introducing a second optical fiber (204), each of longitudinal axes of said fiber introducing grooves (209) matching with each of the corresponding longitudinal axes of said fiber fixing grooves; a movable head (205) facing said optical fiber arranging member (203) and fixing a tip end of said second optical fiber (204); a positioning member (219) provided in said movable head (205) and engaging with said fiber introducing groove (209); a movable arm (228) having said movable head (205) at a tip end thereof, said movable arm (228) having flexibility in the direction of arrangement of said first optical fibers (202) and in the direction perpendicular to the direction of arrangement of said first optical fibers (202); and a drive device (224) for driving said movable arm (228) in a direction of arrangement of said first optical fibers (202) and in a direction perpendicular to the direction of arrangement of said first optical fibers (202) to optically couple said second optical fiber (204) with said first optical fiber (202). An optical switch comprising: an optical fiber arranging member (203) having a plurality of fiber fixing grooves (208) for fixing a plurality of first optical fibers (202) and a plurality of fiber introducing grooves (209) for introducing a second optical fiber (204), each of longitudinal axes of said fiber introducing grooves (209) matching with each of the corresponding longitudinal axes of said fiber fixing grooves (208); an engaging portion (220) formed on the top surface of said optical fiber arranging member (203) and formed along said fiber introducing grooves (209); a movable head (205) facing said optical fiber arranging member (203) and fixing a tip end of said second optical fiber (204); a positioning member (219) provided in said movable head (205) and engaging with said engaging portion (220); a movable arm (228) having said movable head (205) at a tip end thereof, said movable arm (228) having flexibility in the direction of arrangement of said first optical fibers (202) and in the direction perpendicular to the direction of arrangement of said first optical fibers (202); and a drive device (224) for driving said movable arm (228) in a direction of arrangement of said first optical fibers (202) and in a direction perpendicular to the direction of arrangement of said first optical fibers (202) to optically couple said second optical fiber (204) with said first optical fiber (202). The optical switch according to Claim 1 or 2, wherein said positioning member is a guide pin (219) provided on a bottom surface of said movable head (205) and engaging with said fiber introducing groove (209). The optical switch according to Claim 1, 2, or 3, wherein said positioning member is a guide pin (219) provided on a bottom surface of said movable head (205) and engaging with said engaging portion (220) of a V-shape. The optical switch according to Claim 3, or 4, wherein said guide pin comprises at least two guide pins (219) arranged at a pitch of an integral multiple of a pitch of said fiber introducing grooves (209) and in parallel with said second optical fiber (204). The optical switch according to Claim 1, 2, 3, 4, or 5, wherein said movable arm (205) is a combination of a first movable arm (226) with a second movable arm (227) formed by bending respective plate springs into predetermined shapes and arranged at a predetermined distance apart up and down. The optical switch according to Claim 6, wherein said second movable arm (227) is constructed in a zigzag form by connecting a plurality of plate springs (227a), and wherein one end of said second movable arm (227) is fixed to a movable member (232) of said drive mechanism (224) and the other end of said second movable arm is mounted to said movable head (205). The optical switch according to Claim 6 or 7, wherein said second movable arm (296) is formed from a plate spring, a movable head mount portion (266) is formed at a tip of the plate spring, a spring base end (261) is formed at a base end of said plate spring, said plate spring is provided with a first flexible portion (287) extending from said movable head mount portion (266) to said spring base end and integrally formed with said movable head mount portion (266) through a first connecting portion (289), a second flexible portion (285) extending from said spring base end to said movable head mount portion (266) and integrally formed with said spring base end through a second connecting portion (294), and a third flexible portion (286) connecting a tip of said first flexible portion (287) with a tip of said second flexible portion (285) through third and fourth connecting portions (283, 284). The optical switch according to Claim 8, wherein said first flexible portion (287) and said third flexible portion (286) are separated through a first slit portion (275) and wherein said second flexible portion (285) and said third flexible portion (286) are separated through a second slit portion (276). The optical switch according to Claim 8 or 9, wherein said movable head mount portion (266) is inclined upward at a predetermined angle relative to a spring body portion (264) of said plate spring composing said second movable arm (296). The optical switch according to any one of Claims 1 to 10, wherein said drive mechanism (224) is constructed of a first drive mechanism (224A) for driving said movable arm (228) in the direction of arrangement of said first optical fibers (202), and a second drive mechanism (224B) for driving said movable arm (228) in the direction perpendicular to the direction of arrangement of said first optical fibers (202).

Inventors: MAKI HISAO, MURAKAMI TAKASHI, OZAWA KAZUMASA, SAITO KAZUHITO, TOMITA NOBUO, WATANABE TSUTOMU, MAKI, HISAO, MURAKAMI, TAKASHI, OZAWA, KAZUMASA, SAITO, KAZUHITO, TOMITA, NOBUO, WATANABE, TSUTOMU, MAKI, HISAO YOKOHAMA WORKS OF SUMITOMO ELECTRIC, MURAKAMI, TAKASHI YOKOHAMA WORKS OF SUMITOMO ELEC, OZAWA, KAZUMASA YOKOHAMA WORKS OF SUMITOMO ELECTR, SAITO, KAZUHITO YOKOHAMA WORKS OF SUMITOMO ELECTR, WATANABE, TSUTOMU YOKOHAMA WORKS OF SUMITOMO ELEC
Applicants: NIPPON TELEGRAPH & TELEPHONE, SUMITOMO ELECTRIC INDUSTRIES, NIPPON TELEGRAPH AND TELEPHONE CORPORATION, SUMITOMO ELECTRIC INDUSTRIES, LTD.
Application year: 1994
Main classification: G02B26
IPC codes: G02B6